References mentioned in this background section are not admitted to be prior art with respect to the present invention.
The first example is U.S. Pat. No. 6,695,958. This design somewhat resembles the present invention, but is based on a cylinder-shaped cavity with a bottom. Solution is either flowed over or deposited on top of the cavity for detection. The bottom plate does not permit the flow of detectable species through the cylinder-shaped cavity. A key aspect of the present invention is the ease of flow of solution past the electrodes embedded in the walls of the lumen.
The next example is U.S. Pat. No. 7,067,351. This patent describes “A method of forming nanolaminate structures having alternating conductor layers and insulator layers”. The scale and fabrication of this method are quite different than the present invention. In addition, this filing does not specify the use of flow past the electrodes for electrochemical sensing, a key aspect of the present invention.
The final example is U.S. Pat. No. 7,703,336. This invention is an electrochemical flow sensor, wherein a first set of electrodes is used to alter the chemistry of the solution to create a detectable species that is detected further downstream by a second set of electrodes. The time of flight of the created species is used to determine flow rate. The present invention uses a single set of electrodes to measure the change in electrochemical signal that result from flow of an inherent electrochemical species. The present invention requires no change in the chemistry of the solution.